id="functions-hash-note">
   For historical reasons, the function <function>md5</function>
   returns a hex-encoded value of type <type>text</type> whereas the SHA-2
   functions return type <type>bytea</type>.  Use the functions
   <link linkend="function-encode"><function>encode</function></link>
   and <link linkend="function-decode"><function>decode</function></link> to
   convert between the two.  For example write <literal>encode(sha256('abc'),
   'hex')</literal> to get a hex-encoded text representation,
   or <literal>decode(md5('abc'), 'hex')</literal> to get
   a <type>bytea</type> value.
  </para>

  <para>
   <indexterm>
    <primary>character string</primary>
    <secondary>converting to binary string</secondary>
   </indexterm>
   <indexterm>
    <primary>binary string</primary>
    <secondary>converting to character string</secondary>
   </indexterm>
   Functions for converting strings between different character sets
   (encodings), and for representing arbitrary binary data in textual
   form, are shown in
   <xref linkend="functions-binarystring-conversions"/>.  For these
   functions, an argument or result of type <type>text</type> is expressed
   in the database's default encoding, while arguments or results of
   type <type>bytea</type> are in an encoding named by another argument.
  </para>

  <table id="functions-binarystring-conversions">
   <title>Text/Binary String Conversion Functions</title>
   <tgroup cols="1">
    <thead>
     <row>
      <entry role="func_table_entry"><para role="func_signature">
       Function
      </para>
      <para>
       Description
      </para>
      <para>
       Example(s)
      </para></entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry role="func_table_entry"><para role="func_signature">
       <indexterm>
        <primary>convert</primary>
       </indexterm>
       <function>convert</function> ( <parameter>bytes</parameter> <type>bytea</type>,
       <parameter>src_encoding</parameter> <type>name</type>,
       <parameter>dest_encoding</parameter> <type>name</type> )
       <returnvalue>bytea</returnvalue>
      </para>
      <para>
       Converts a binary string representing text in
       encoding <parameter>src_encoding</parameter>
       to a binary string in encoding <parameter>dest_encoding</parameter>
       (see <xref linkend="multibyte-conversions-supported"/> for
       available conversions).
      </para>
      <para>
       <literal>convert('text_in_utf8', 'UTF8', 'LATIN1')</literal>
       <returnvalue>\x746578745f696e5f75746638</returnvalue>
      </para></entry>
     </row>

     <row>
      <entry role="func_table_entry"><para role="func_signature">
       <indexterm>
        <primary>convert_from</primary>
       </indexterm>
       <function>convert_from</function> ( <parameter>bytes</parameter> <type>bytea</type>,
       <parameter>src_encoding</parameter> <type>name</type> )
       <returnvalue>text</returnvalue>
      </para>
      <para>
       Converts a binary string representing text in
       encoding <parameter>src_encoding</parameter>
       to <type>text</type> in the database encoding
       (see <xref linkend="multibyte-conversions-supported"/> for
       available conversions).
      </para>
      <para>
       <literal>convert_from('text_in_utf8', 'UTF8')</literal>
       <returnvalue>text_in_utf8</returnvalue>
      </para></entry>
     </row>

     <row>
      <entry role="func_table_entry"><para role="func_signature">
       <indexterm>
        <primary>convert_to</primary>
       </indexterm>
       <function>convert_to</function> ( <parameter>string</parameter> <type>text</type>,
       <parameter>dest_encoding</parameter> <type>name</type> )
       <returnvalue>bytea</returnvalue>
      </para>
      <para>
       Converts a <type>text</type> string (in the database encoding) to a
       binary string encoded in encoding <parameter>dest_encoding</parameter>
       (see <xref linkend="multibyte-conversions-supported"/>